I found this explanation on the internet: ‘a word or phrase used in a non-literal sense for rhetorical or vivid effect.’

We as writers should not use these in our writing because most people might not understand their use.  I think it sometimes adds a degree of whimsy to the story.

I remember some years ago when I working with a Russian chap who’d not been in the country very long, and though he had a reasonable use of English, it was not quite up with our figures of speech.

And made me realize when he kept asking me what they meant, just how many I used in everyday use.

Most of these figures of speech use descriptions that do not necessarily match the word being described, such as ‘I dance like I have two left feet’.

And that pretty much sums up how good I can dance.  But …

‘Like a bat out of hell’, not sure how this got into the vernacular

‘Like a bull in a china shop’, describes a toddler let loose, no, you had the securely in their pram but somehow they got loose while you weren’t looking

‘More front than Myers’, as my mother used to say, but in context, Myers is the Australian version of the English Selfridges or Harrods or Paris Galleries Lafayette.  It refers to the width of street frontage of the stores, which in fact stretched for a whole block

‘As mad as a hatter’, though not necessarily of the millinery kind, but, well, you can guess, it’s from Alice in Wonderland

‘As nutty as a fruitcake’, provided your fruitcake has nuts in it

And, ‘I haven’t heard from him in donkey’s years’ which means you haven’t heard from someone for a long time, or perhaps as long as it takes donkey’s ears to fully grow.

Yes, someone made a minor adjustment and added a y to ears, because it used to be ‘donkey’s ears’, believe it or not.

You can see, if you get the references, they are somewhat apt, and, yes, they sometimes creep into my stories.